package com.wc.alorithm_blue_bridge._思维.阶乘的和;

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.PrintWriter;
import java.util.StringTokenizer;
import java.util.TreeMap;

/**
 * @Author congge
 * @Date 2024/3/25 10:52
 * @description https://www.lanqiao.cn/problems/3527/learning/?page=1&first_category_id=1
 */
public class Main {
    static FastReader sc = new FastReader();
    static PrintWriter out = new PrintWriter(System.out);
    static int N = 100010;
    static int[] a = new int[N];
    static int n;

    // 思路：合并 1 1 -> 2   2 2 2 -> 3  3 3 3 3 -> 4 合并下去，直至合并不了，就说明没有下一个数可以表达出来了
    public static void main(String[] args) {
        n = sc.nextInt();
        TreeMap<Integer, Integer> map = new TreeMap<>();
        for (int i = 1; i <= n; i++) {
            a[i] = sc.nextInt();
            map.put(a[i], map.getOrDefault(a[i], 0) + 1);
        }

        while (map.firstKey() != null) {
            int num = map.firstKey();
            int cnt = map.get(num);
            map.remove(num);
            if (cnt % (num + 1) == 0) {
                map.put(num + 1, map.getOrDefault(num + 1, 0) + cnt / (num + 1));
            } else {
                System.out.println(num);
                return;
            }
        }
    }
}

class FastReader {
    StringTokenizer st;
    BufferedReader br;

    FastReader() {
        br = new BufferedReader(new InputStreamReader(System.in));
    }

    String next() {
        while (st == null || !st.hasMoreElements()) {
            try {
                st = new StringTokenizer(br.readLine());
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
        return st.nextToken();
    }

    int nextInt() {
        return Integer.parseInt(next());
    }

    String nextLine() {
        String s = "";
        try {
            s = br.readLine();
        } catch (IOException e) {
            e.printStackTrace();
        }
        return s;
    }

    long nextLong() {
        return Long.parseLong(next());
    }

    double nextDouble() {
        return Double.parseDouble(next());
    }

    // 是否由下一个
    boolean hasNext() {
        while (st == null || !st.hasMoreTokens()) {
            try {
                String line = br.readLine();
                if (line == null)
                    return false;
                st = new StringTokenizer(line);
            } catch (IOException e) {
                throw new RuntimeException(e);
            }
        }
        return true;
    }
}
